Cathar is right, there is a conflict of interest.
However... the conflict as described (by Cathar) is
competitive against other cooling solutions, which, IMO, is pretty broad, but still valid. The proposed disclaimer would be appropriate.
Something needs to be cleared up though; at issue is not that Joe has used his testing (so far) to create a product; nothing wrong has been done, and no one has claimed such.
No one has reason to believe that Joe has falsified any tests to otherwise promote his product. The issue is that this potential now exists.
Since Joe now has his own product, some manufacturers may refuse to send him samples, which then skews the entire testing effort.
As for the "independant testing" of the current product, I believe that it would best be called "testing by a 3rd party", but I suspect that there's going to be more to it than that.
Many products have been promoted as being "better than the competition" but we all know that the credibility there is pretty slim. Not even Swiftech publishes numbers about other waterblocks; it's rather pointless. Instead, Swiftech has published results on their site of a " Competitive review, courtesy Procooling.com" (here:
http://swiftnets.com/products/mcw6000.asp# ).
I also plan to test a few water block designs of my own, and if I came up with one that would be marketable, I'd be facing the same thing; I'd have to drop one or the other. Effectively, that puts me in a conflict of interest, right now.
If Joe was hired as a consultant for a third party to advise them on a particular design issue, or otherwise assist them on a design, that would also be questionable.
Then again, we don't know if there might have been any kind of agreement, prior to testing any particular units, which would have covered any such thing. No one in the general public has been made aware of such.